* [Intel-gfx] [PATCH] drm/i915/gt: Pull checking rps->pm_events under the irq_lock
@ 2020-03-10 12:59 Chris Wilson
0 siblings, 0 replies; only message in thread
From: Chris Wilson @ 2020-03-10 12:59 UTC (permalink / raw)
To: intel-gfx
Avoid angering kcsan by serialising the read of the pm_events with the
write in rps_diable_interrupts.
[ 6268.713419] BUG: KCSAN: data-race in intel_rps_park [i915] / rps_work [i915]
[ 6268.713437]
[ 6268.713449] write to 0xffff8881eda8efac of 4 bytes by task 1127 on cpu 3:
[ 6268.713680] intel_rps_park+0x136/0x260 [i915]
[ 6268.713905] __gt_park+0x61/0xa0 [i915]
[ 6268.714128] ____intel_wakeref_put_last+0x42/0x90 [i915]
[ 6268.714352] __intel_wakeref_put_work+0xd3/0xf0 [i915]
[ 6268.714369] process_one_work+0x3b1/0x690
[ 6268.714384] worker_thread+0x80/0x670
[ 6268.714398] kthread+0x19a/0x1e0
[ 6268.714412] ret_from_fork+0x1f/0x30
[ 6268.714423]
[ 6268.714435] read to 0xffff8881eda8efac of 4 bytes by task 950 on cpu 2:
[ 6268.714664] rps_work+0xc2/0x680 [i915]
[ 6268.714679] process_one_work+0x3b1/0x690
[ 6268.714693] worker_thread+0x80/0x670
[ 6268.714707] kthread+0x19a/0x1e0
[ 6268.714720] ret_from_fork+0x1f/0x30
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/gt/intel_rps.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_rps.c b/drivers/gpu/drm/i915/gt/intel_rps.c
index 506738dede16..dbecfb5a5bb1 100644
--- a/drivers/gpu/drm/i915/gt/intel_rps.c
+++ b/drivers/gpu/drm/i915/gt/intel_rps.c
@@ -1459,12 +1459,12 @@ static void rps_work(struct work_struct *work)
u32 pm_iir = 0;
spin_lock_irq(>->irq_lock);
- pm_iir = fetch_and_zero(&rps->pm_iir);
+ pm_iir = fetch_and_zero(&rps->pm_iir) & rps->pm_events;
client_boost = atomic_read(&rps->num_waiters);
spin_unlock_irq(>->irq_lock);
/* Make sure we didn't queue anything we're not going to process. */
- if ((pm_iir & rps->pm_events) == 0 && !client_boost)
+ if (!pm_iir && !client_boost)
goto out;
mutex_lock(&rps->lock);
--
2.20.1
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